from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun A soft, black to dark gray mineral, MnO2, the commonest and most important secondary ore of manganese.

from The Century Dictionary.

  • noun Native manganese dioxid (MnO2), a common ore of manganese, occurring crystallized and massive, of a gray-color and metallic luster.

from the GNU version of the Collaborative International Dictionary of English.

  • noun (Min.) Manganese dioxide, a mineral of an iron-black or dark steel-gray color and metallic luster, usually soft. Pyrolusite parts with its oxygen at a red heat, and is extensively used in discharging the brown and green tints of glass (whence its name).

from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • noun mineralogy A dark coloured mineral, consisting of manganese dioxide (MnO2), that is an important ore of manganese.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

  • noun a mineral consisting of manganese dioxide; an important source of manganese


from The American Heritage® Dictionary of the English Language, 4th Edition

[German Pyrolusit : Greek puro-, pyro- + Greek lousis, a washing (from louein, to wash; see leu(ə)- in Indo-European roots).]


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  • The most important mineral is pyrolusite, because it is the main ore mineral for manganese.


  • The heat and carbon in the charcoal separated oxygen from the pyrolusite, leaving a metallic manganese residue.


  • In 1774, while heating the mineral pyrolusite (MnO2, manganese dioxide) in a charcoal fire, the Swedish scientist Johann Gahn discovered manganese.


  • Traces of pyrolusite in a chunk of raw glass, the result of a failure to produce colorless glass at Sagalassos

    Interactive Dig Sagalassos - Glass Studies

  • One special find this week was a chunk of raw glass, showing an unhomogeneous color, probably as a result of an insufficient or failed addition of decolorant in a reduced furnace atmosphere (e.g. manganese in the form of the mineral pyrolusite).

    Interactive Dig Sagalassos - Glass Studies

  • ~ Manganese is found in nature chiefly as the dioxide MnO_ {2}, called pyrolusite.

    An Elementary Study of Chemistry

  • _ In the laboratory chlorine is made by warming the mineral pyrolusite (manganese dioxide, MnO_ {2}) with concentrated hydrochloric acid.

    An Elementary Study of Chemistry

  • The periodic process depends on the interaction between manganese dioxide (pyrolusite), sulphuric acid, and a bromide, and the operation is carried out in sandstone stills heated to 60°

    Encyclopaedia Britannica, 11th Edition, Volume 4, Part 3 "Brescia" to "Bulgaria"

  • ~ While studying the action of hydrochloric acid upon the mineral pyrolusite, in 1774, Scheele obtained a yellowish, gaseous substance to which he gave a name in keeping with the phlogiston theory then current.

    An Elementary Study of Chemistry

  • How does pyrolusite effect the decolorizing of glass containing iron?

    An Elementary Study of Chemistry


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